IEEE Access IEEE Access Noninvasive Monitoring of Potassium Fluctuations During the Long Interdialytic Interval Rodrigues A.S. Petrenas A. Paliakaite B. Kusleikaite-Pere N. Jarusevicius G. Bumblyte I.A. Laguna P. Universidad de Zaragoza Marozas V. 2020 research-article